1. Field of the Invention
The present invention relates to an image-blur correction device having an image-blur correction function, and an image pickup device, such as a digital still camera or a video camera, and an optical device, which include the image-blur correction device.
2. Description of the Related Art
In recent years, techniques of miniaturization, weight reduction, and high-magnification zooming for image pickup devices, such as digital still cameras, have been developed, and an adverse effect of camera-shake has been noted. To address this disadvantage, image pickup devices including a function of correcting image-blur, that is, an image-blur correction function, have been increasingly proposed.
Such image-blur correction functions are roughly categorized into an optical function and an electronic function. In most of the image-blur correction functions, blur is detected using a sensor which detects vibration generated due to camera-shake. On the other hand, in small, light image pickup devices which are attached to cellular phones, for example, an amount of blur is calculated by detecting a motion vector based on a displacement of an image captured using an image-capturing unit.
In the optical image-blur correction, image-blur is corrected by moving a shift lens or an image pickup device in a direction in which an amount of detected blur is cancelled. In the electronic image-blur correction, image-blur is corrected by performing image processing so that an amount of calculated blur is cancelled. Furthermore, an image pickup device having a mechanism in which an axis used for detecting an amount of image-blur and a correction axis (lens driving axis) of a compensation lens used to correct the image-blur are arranged to be rotated so that miniaturization, weight reduction, and high-magnification zooming are achieved has been developed (Refer to Japanese Patent Laid-Open No. 8-152661).
However, as a distance between a lens and the center of an optical axis becomes large, attenuation of light quantity becomes large substantially in proportion to the distance. This causes deterioration of an image. Therefore, a lens-movable range is restricted in a predetermined range. In a lens driving method in the related art, an amount of displacement (an amount of lens driving control) is restricted once with respect to the detection axis or the correction axis so that the lens-movable range has a rectangular shape. FIG. 5A (which will be described hereinafter) shows a state in which an amount of displacement is restricted with respect to a detection axis and a lens-movable range is determined so as to have a rectangular shape.
However, in the lens driving method in the related art, a problem arises in that although a lens is usable in a circular region, the lens is actually movable in a rectangular region. Therefore, when the movable region is included in the circular region which is performance limit of the lens, a large portion (which corresponds to an area obtained by subtracting an area of the rectangular region from the circular region) of the lens usable region is not used.